Magnetic materials suitable for use in relays, ringers, and electro-acoustic transducers such as loudspeakers and telephone receivers characteristically exhibit high values of magnetic coercivity, remanence, and energy product.
Among established alloys having suitable magnetic properties are Al-Ni-Co-Fe and Cu-Ni-Fe alloys which are members of a group of alloys considered to undergo spinodal decomposition resulting in a fine-scale two-phase microstructure. Recently, alloys containing Fe, Cr and Co have been investigated with regard to potential suitability in the manufacture of permanent magnets. Specifically, certain ternary Fe-Cr-Co alloys are disclosed in H. Kaneko et al, "New Ductile Permanent Magnet of Fe-Cr-Co Systems", AIP Conference Proceedings No. 5, 1972, p. 1088, and in U.S. Pat. No. 3,806,336, "Magnetic Alloys". Quaternary alloys containing ferrite forming elements such as, e.g., Ti, Al, Si, Nb, or Ta in addition to Fe, Cr, and Co are disclosed in U.S. Pat. No. 3,954,519, "Iron-Chromium-Cobalt Spinodal Decomposition Type Magnetic Alloy Comprising Niobium and/or Tantalum", in U.S. Pat. No. 3,989,556, "Semihard Magnetic Alloy and a Process for the Production Thereof", in U.S. Pat. No. 3,982,972, "Semihard Magnetic Alloy and a Process for the Production Thereof", and in U.S. Pat. No. 4,075,437, "Composition, Processing, and Devices Including Magnetic Alloy".
The use of ferrite forming elements such as, e.g., Ti, Al, Si, Nb or Ta in quaternary alloys has been advocated, especially at higher Co levels or in the presence of impurities such as, e.g., C, N, or O, to facilitate production of a preliminary fine-grained alpha phase structure by low-temperature annealing.